1. Field of the Invention
The present invention relates to a method of manufacturing a wiring circuit board, and more specifically, it relates to a method of manufacturing a wiring circuit board such as a COF board.
2. Description of Related Art
In general, an additive process is employed for forming a conductive pattern of a wiring circuit board such as a COF board. For example, there is proposed an additive process of forming a conductive thin film made of chromium and copper on an insulating base layer made of polyimide and forming a conductive pattern made of copper on the conductive thin film (refer to Japanese Unexamined Patent Publication No. 2006-332549, for example).
According to the aforementioned Japanese Unexamined Patent Publication No. 2006-332549, the conductive thin film is formed on the overall surface of the insulating base layer by sputtering. Then, the conductive thin film is covered with a negative dry film resist, thereafter exposed from above through a photomask and then developed, thereby forming a plating resist in a reversal pattern of a wiring circuit pattern. Then, the conductive pattern is formed on the surface of the conductive thin film exposed from the plating resist by deposition of copper by electrolytic copper plating.